Led with substrate modifications for enhanced light extraction and method of making same

• US 20090233394A1
• Filed: 04/01/2009
• Published: 09/17/2009
• Est. Priority Date: 07/02/2004
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Ibbetson, James, Li, Ting, Saxler, Adam W., Batres, Max
• Granted Patent: US 8,617,909 B2
• Time in Patent Office: Days
• US Class Current: 438/43
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10155 being other than a cuboid
• CPC Class Codes: H01L 2924/10158 at the passive surface
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. Etched features, such as truncated pyramids, may be formed on the emitting surface, prior to the RIE process, by cutting into the surface using a saw blade or a masked etching technique. Sidewall cuts may also be made in the emitting surface prior to the RIE process. A light absorbing damaged layer of material associated with saw cutting is removed by the RIE process. The surface morphology created by the RIE process may be emulated using different, various combinations of non-RIE processes such as grit sanding and deposition of a roughened layer of material or particles followed by dry etching.

Claims

1. A method of fabricating a light emitting diode (LED) including a substrate having a light emitting surface, said method comprising:

applying a reactive ion etch (RIE) process to at least a portion of the light emitting surface for a time duration sufficient to change the morphology of the surface.

2. The method of claim 1 wherein the RIE process is an inductively coupled plasma reactive ion etch (ICP-RIE) process.

3. The method of claim 1 further comprising growing a light emission region on the surface of the substrate opposite the emission surface.

4. The method of claim 3 wherein the RIE process is applied prior to growing the light emission region.

5. The method of claim 3 wherein the RIE process is applied after growing the light emission region.

6. The method of claim 1 further comprising forming a plurality of etched features associated with the light emitting surface prior to applying the RIE process.

7. The method of claim 6 wherein the etched features are formed by cutting a plurality of bevels into the light emitting surface.

8. The method of claim 7 wherein the cutting is done using an angled saw blade.

9. The method of claim 7 wherein the cutting is done using a masked etching technique.

10. The method of claim 1 further comprising forming a plurality of sidewall cuts associated with the light emitting surface prior to applying the RIE process.

11. A method of fabricating an LED including a substrate having a light emitting surface having at least one cut surface with a light absorbing damaged layer of material, said method comprising:

applying a reactive ion etch (RIE) process to the cut surface for a time duration sufficient to remove at least a portion of the damaged layer of material.

12. The method of claim 11 wherein the RIE process is an inductively coupled plasma reactive ion etch (ICP-RIE) process.